1. Field of the Invention
The present invention relates to a method of manufacturing a cutting tool of which only a cutting part is formed of cemented carbides, and more particularly, to a method of manufacturing a cemented carbide cutting tool having high mechanical property as cracks in the cemented carbide cutting tool do not generate even after a high temperature coating process, and a cutting tool manufactured by the method.
2. Related Art
Cutting tools such as an end-mill used in a milling machine, a drill for machining an aperture, and a cold and hot punch include a cutting part at a front end thereof, and a shank part integrally formed with the cutting part. The cutting tools should have excellent mechanical properties such as durability, wear resistance and machinability, and thus are generally manufactured of hard metal.
However, since cemented carbides used as a tool material is very expensive, the cutting tools in which only the cutting part except the shank part is formed of cemented carbides are manufactured.
A related art document 1 (Korean Utility Model Registration No. 20-0256477) discloses a carbide tipped brazed tool of which a shank part is formed of tool steel, and a cutting part is formed of cemented carbides wherein a nickel thin sheet is inserted into a butt joint portion between the shank part and the cutting part and then to integrally form the shank part with the cutting part by brazing. Also, a related art document 2 (Korean Patent No. 10-1099395) discloses a cemented carbide cutting tool including a machining part of a cemented carbide material and a supporting part of a general metal, and a manufacturing method thereof wherein processed powders used as a starting material for the machining part and the supporting part are sintered in a vacuum chamber by spark plasma sintering and integrally formed.
As described above, in the related art documents 1 and 2, only the cutting part, i.e., the machining part is formed of cemented carbides, and thus a manufacturing cost of the tool may be reduced.
Here, in the case of another cutting tool as well as the cemented carbide cutting tools disclosed in the related art documents, an additional process of coating a diamond film or a titanium aluminum nitride on the surface of the tool was required to provide for excellent mechanical properties such as durability, wear resistance and machinability.
However, in the case of a cutting tool in which both of the shank part and the cutting part are formed of cemented carbides, there occurs no problem in the above coating while in the case of another cutting tool in which only the cutting part is formed of cemented carbides, cracks may occur at the surface of the tool after a heat treatment applied upon the coating process since the shank part and the cutting part have different thermal expansion coefficients from each other.